Examples of systems that have been put into practical application as parking assistance apparatus for assisting driving operation during parking include a system for automatically steering and guiding a vehicle to a set parking target position, a system for indicating steering direction and steering amount to the driver, and other systems. Conventionally, when setting the parking target position, the driver has needed to operate input means provided inside the vehicle, such as a monitor device with setting switches and a touch panel. In response to this, parking assistance apparatus has been proposed in which a parking target position can be set without input means that are not used in normal driving operations. Japanese Laid-open Patent Application No. 2008-201363 (Patent Document 1) discloses a parking assistance apparatus for setting a parking mode and a parking target position on the basis of the driver's operation of the steering wheel. Thereby, when the steering wheel is operated a predetermined amount or more to either the left or right, a parking target position corresponding to parking in a garage to the left or right is set. When the steering wheel is not operated a predetermined amount or more to either the left or right, a parking target is set which corresponds to parallel parking to the left (Patent Document 1: FIGS. 5 and 9, paragraphs 27 to 36, etc.).
The set parking target position is set automatically by the parking assistance apparatus in relation to position of the vehicle (FIG. 7 of the Patent Document 1, for example). Therefore, the driver does not have much freedom in selecting the parking target position relative to the vehicle. Even when a plurality of parking spots are open in a parking lot of a shopping center or the like, for example, and the driver intends to park in a spot near the entrance/exit, there are cases in which the spot that is set is different from the driver's desired spot in terms of the positional relationship to the vehicle. In other words, even though the parking assistance apparatus of Patent Document 1 allows for the selection of a plurality of parking target positions, the parking modes and the parking target positions have a one-to-one correspondence. Specifically, even through the parking mode can be selected, the parking target position is defined unambiguously in any parking mode, and it is not possible to select any desired parking target position.
Setting the parking target position is not limited to setting in relation to the position of the vehicle as in Patent Document 1. As disclosed in Japanese Laid-open Patent Application No. 2007-290557 (Patent Document 2), for example, there are also methods for using sonar or the like to detect open space while the vehicle is traveling, methods for recognizing images of white lines indicating parking spots, and other methods (Patent Document 2: FIGS. 2 and 5, paragraphs 27 and 45, and the like). However, in either of these methods, the driver is unable to set any desired parking target position in a simple manner without using input means that are not used during normal driving operation. In Patent Document 2, a first target parking position and a second target position can be selected, and it is possible to select among open spaces detected using sonar or the like while the vehicle is traveling as well as parking spots where images of white lines are recognized. However, the parking assistance apparatus automatically makes this selection on the basis of the likelihood of the detection result, and this is not a system that allows the driver to set any desired parking target position.